In [1], J. Bosch, J. M. Aniceto, “Potenziale für das Lastmanagement im Bahnenergiesystem” (potentials for the load management in a railway energy system), eb—Elektrische Bahnen, issue 2, 2013, it is described, that the superposition of traction powers at specific points in time can cause considerable load fluctuations in the energy supply of railway systems. For covering such peak loads the required energy, which is defined by the maximum peak load and an energy reserve, must be allocated by power plants, often involving frequency transformation. Hence, a rise of peak loads in the future demands investments into the expansion of the energy supply system. Furthermore, energy for peak loads, which are provided by power plants that are designed for quickly meeting immediate energy demands, is costly, wherefore peak loads are normally avoided by load management.
[2], J. Bosch, Frequenzkomponenten des Bahnstromlastgangs—Zusammenhänge mit dem Bahnbetrieb (load oscillations of the rail current course—interdependencies with the railway operation), eb—Elektrische Bahnen, issue 4, 2014, shows a daily course of the total load in a power grid, namely the power grid of the Swiss Federal Railways, which exhibits peak loads in time ranges around 08:00 and 18:00. Further, frequencies of this load curve are shown, which are determined by a Fourier transform of the load curve. It is shown that due to the application of synchronised timetables significant load changes with a cycle duration of 1 minute and 30 minutes occur. Hence, peak loads occur particularly at times, at which the different periodic load changes simultaneously exhibit a maximum value.
In [1] it is describes that peak loads can be avoided by removing system units with lower priority from the power grid, so that peak loads are avoided while the operation of the railway system can be maintained. Load management can be controlled centrally or peripherally. With the peripheral control the power consumption is locally optimised for each system unit or train system, e.g. by reducing power supplied to the heating systems in times when the related train requires high traction power. With the central control, peak loads are centrally detected and control signals are sent out to switch peripheral system units. In this way, all participating system units can simultaneously be used for the load management. For the communication existing communication networks can be used and expanded. With the known load management systems, system units that are not essential, are typically deactivated e.g. between 7:00 and 9:00 or between 14:00 and 22:00, i.e. in times in which power consumption is high. Hence, system units or loads are typically removed from the power grid over longer time periods, in in which higher power consumption is expected.
However, deactivating loads, e.g. heating systems, over a longer period of time typically leads to a reduction in comfort for passengers and possibly causes functional restrictions in the railway system. Furthermore, it is possible that loads are deactivated unnecessarily, as it may turn out afterwards that power consumption has been less than expected. Furthermore, surprisingly, individual peak loads can sporadically occur outside the time ranges, in which loads are removed from the power grid. Hence, these peak loads, which can cause instabilities in the power grid of the technical system, are not taken into account by load management.
[3], EP2505416B1, discloses a method for allocating electrical energy for a railway system, with the steps of determining the trains in operation and their driving parameters; determining the load state in the power grid of the railway system; increasing the speed of at a train above a scheduled speed if the load state below an optimum load and reducing the speed of at least one rail vehicle for regenerative feed-in of electrical energy if the load state is above an optimum load.
This method is based on the measurement of the current load state and requires therefore short-term interventions into the railway system. The effects of the corrective measures, which are executed during an overload of the power grid, are insignificant. Furthermore, short-term interventions into the handling of travelling trains are rather undesirable.
[4], EP2799307A1, discloses a control device, with which a group of trains travelling in a railway system are controlled depending on train diagrams and a predetermined maximum power consumption such that the current power consumption lies below the maximum power consumption. For this purpose the control device establishes, based on train diagrams and train timetables resulting therefrom, a plan for the energy requirement and determines load values, which exceed the predetermined maximum power consumption.
This method requires significant efforts, since the loads need to be calculated for all occurring combinations of the individual loads of the vehicles for a complete day. For all changes of the timetables the calculations need to be repeated, whereby all these calculations are always based on assumptions, which often deviate from reality.
[5], JPH0516808, discloses a management system or a substation of the power grid of a railway system, which is assigned to a track section on which a plurality of trains can travel. The management system shall allow changing of timetables under the consideration of delays of individual trains, in order to avoid an overload of the power grid in this track section. In the event that individual trains are delayed, a significant increase in the train density in this track section can occur.
If trains with an earlier departure time are delayed and following trains travel are on time, then e.g. instead of three trains possibly seven to eight trains may travel in the same track section at the same time (see FIG. 8). In times, in which, due to train delays, higher train densities occur, the load on the substation increases, wherefore delays are determined by fuzzy logic and changes in the timetable are executed in accordance with the expected higher densities.
[6], JPH0834268A, proposes a method for the prediction of the load on a power grid of a railway system exploiting the fact that the power requirement of a train when travelling along the track section strongly depends on executed accelerations. Data of timetables and properties of individual train are handed over from a first unit, which calculates travel data, to a second unit, which calculates for the following time period the travel paths and the accelerations for each train. Based on accelerations calculated for the individual trains, a third unit determines the expected load on the power grid in a substation. Hence, with considerable efforts and based on determining travel data and the status and behaviour of the individual trains, future loads are calculated for a small section of the railway system.
Hence, prior art discloses solutions with which loads of section of the power grid of a railway system are determined by means of timetables and monitoring of the status and behaviour of the trains. For this purpose, with considerable effort, positions of the individual trains, possible delays with respect to a timetable as well as remaining distances and accelerations need to be determined with considerable efforts in order to be able to apply corrective measures in parts of the power grid.